People's mental model of the world doesn't include principal-agent problems[1]. People with actual equity in competing businesses tend to be pretty rivalrous (e.g. owners of small independent restaurants on the same street); naively, if you don't see employees as anything more than extensions of those rivalrous owners, you'd expect them to behave the same. But instead, of course, "it's just a job."
It wasn't just me, there were also Canon and Epson reps there. Being that we were all basically coworkers (as we had the same jobs), we were very jovial toward each other, but customers would often remark that we should be more hostile toward each other, usually in jest -- still it made me realize how little they understood our day to day jobs, and how little people consider pragmatism in their observances.